Generally, RFID cards function to wirelessly send and receive product information via frequencies, are already included in subway and bus cards and widely used in daily life, and are also called smart tags or smart labels.
Such RFID cards are advantageous over barcode systems, which carry information on strip images, in that they can wirelessly process information rapidly, and the technology thereof has advanced at present to the level where product information can be wirelessly and immediately read within predetermined distances.
Such RFID cards do not require users to stop and wait for the processing of the information of the RFID cards because card terminals process the information in a time period shorter than 100 ms (0.1 seconds) when card holders pass the RFID cards over the antenna boxes of the terminals within recognition distances. Furthermore, such RFID cards can be manufactured to have sizes equal to or smaller than those of existing credit cards, so that the reading of the RFID cards is enabled while the RFID cards are put in purses or carried as accessories, thereby providing convenience to users. The illicit use of the RFID cards can be prevented by encrypting data, and fixed serial numbers are contained in respective RFID cards, so that the uniqueness and security of the RFID cards is high, and thus the RFID cards have excellent functionality, including convenience of use, thereby providing convenience to card holders.
Such RFID cards are international standard ISO cards, and are classified into a plurality of types.
That is, ISO 14443A-type cards, ISO 14443B-type cards and ISO 15693-type cards are based on the international standards of RFID cards for 13.56 MHz. Each 13.56 MHz tag includes an RFID chip capable of storing information and a loop antenna, that is, a coil surrounding the RFID chip. When the RFID chip is brought within the range of recognition of the terminal, an inductive magnetic field is generated from the loop antenna, that is, a coil, so that data stored by a program stored in the RFID chip is sent to the terminal.
With regard to the 13.56 MHz tag, the distance of recognition between the terminal and the tag varies depending on the construction of the loop antenna, and it is chiefly used in traffic cards because the distance of recognition from the terminal is short.
Furthermore, ISO 18000-type cards are based on the international standards of RFID cards for 900 MHz. Each of the 900 MHz tags includes an RFID chip, capable of storing data in memory, and a UHF antenna, capable of receiving a carrier from a terminal. When the 900 MHz tag receives a carrier from the terminal, the RFID chip contained in the tag reacts thereto and thus sends the content of the memory to the terminal.
Such 900 MHz tags are chiefly used for logistics management, personnel and vehicle entry control, and attendance management due to their long distances of recognition from terminals.
Meanwhile, ISO 11784-type cards are based on the international standards of RFID cards for 134 KHz, and are used for the management of animals. ISO 7816 cards are based on the international standards of RFID cards for smart cards, are electronic cards onto the surfaces of which Integrated Circuit (IC) RFID chips, each containing a 8-bit or 32-bit Micro Processor Unit (MPU) having its own operation function, a Crypto Operating System (COS) and EEPROM, that is, a secure storage space, are attached, and are mainly used as electronic money or the like in the financial field.
FIG. 1 is a diagram showing the construction of an RFID card including a typical RFID tag. In the RFID card, a loop antenna 12, formed by arranging several turns of thin copper line or printing such a conductive line in conductive ink, is disposed along the peripheral portion of the upper surface of a base sheet 11, and the RFID chip 13, connected to the loop antenna 12 and configured to store various types of information and communicate with a terminal, is installed on one side of the upper surface of the base sheet 11.
Protective sheets 14 and 15, provided with a function of protecting the loop antenna 12 and the RFID chip 13 on the base sheet 11 and provided with printed advertisements, are respectively disposed on and beneath the base sheet 11, and transparent film sheets 17 and 18, configured to protect advertisements 16 printed on the surfaces of the protective sheets 14 and 15, are respectively stacked on the outer surfaces of the protective sheets 14 and 15.
The conventional RFID card 10, constructed as described above, is configured such that, when a user brings the RFID card 10 near a terminal (not shown), a high-frequency band frequency in a high frequency band, transmitted from the terminal, is induced to the loop antenna 12, and thus an electromotive force is generated, so that the electromotive force is supplied to the RFID chip 13 as drive power.
When drive power is supplied to the RFID chip 13 via the loop antenna 12, various types of information are sent to the terminal via the loop antenna 12 by the program, and then information is processed, so that the RFID chip 13 and the terminal perform bidirectional communication via the loop antenna 12.
Most such conventional RFID cards are incinerated in the case where they cannot be used because the RFID chips 13 or the loop antennas 12 are damaged or in the case where they are discarded because the life spans thereof have expired. In this case, there is a problem in that environmental hormones, toxic to human bodies, are discharged from the base sheet 11, the protective sheets 14 and 15, and the transparent film sheets 17 and 18, made of polyvinyl chloride (PVC), thereby causing air contamination.
In order to solve the conventional problem, a paper-type RFID tag is proposed in Korean Unexamined Patent No. 2005-79621. The paper-type RFID tag is illustrated in FIGS. 2 and 3.
That is, FIG. 2 is a diagram showing a process of manufacturing the conventional paper RFID card, and FIG. 3 is a sectional view of the paper RFID card completed through the process shown in FIG. 2. The paper RFID card is manufactured through a process of manufacturing a metallic foil laminate, a process of forming a resin layer, a process of manufacturing an antenna pattern, a process of attaching a protective tape, an ultrasonic mounting process, a process of forming a thread, and a paper making process.
First, in the process of manufacturing a metallic film laminate, a metallic foil laminate 30 is constructed by stacking an aluminum metallic foil 32 having a thickness of about 7 μm, used to form an antenna, on a polyester film 33 having a thickness of about 12 μm, configured to form a thread 37, as shown in FIG. 2(A).
In the process of forming a resin layer, a resin layer 31 having a thickness ranging from 1 to 6 μm is formed on the surface of the aluminum metallic foil 32 of the metallic foil laminate 30 in the form of an antenna pattern, as shown in FIG. 2(B). This resin layer 31 is made using material that functions as a resist when the aluminum metallic foil 32 is processed through etching in the subsequent process.
In the process of manufacturing an antenna pattern, an antenna 32a is formed by eliminating portions of the aluminum metallic foil 32 exposed outside the resist of the antenna pattern of the resin layer 31 through etching, as shown in FIG. 2(C).
In the protective member attachment process, a protective member 34, which is a polyester film capable of withstanding high roll load in the following paper making process and having stiffness higher than a paper layer, and which is provided with openings 35, is fixedly adhered to the antenna 32a and the resin layer 31 using an adhesive, as shown in FIG. 2(D).
In the ultrasonic mounting process, an RFID chip 13 is inserted and pressed into each of the openings 35 formed above the antenna 32a and the resin layer 31, and lateral vibrations are applied to the top surface of the RFID chip 13, so that the metallic bump of the RFID chip 13 removes the resin layer 31 and comes into contact with the antenna 32a, as shown in FIG. 2(E).
In the process of forming the thread 37, RFID threads 37 are formed by cutting the RFID chip 13, the protective member 34, the antenna 32a, and the polyester film 33, which are stacked one on top of another, into individual units, as shown in FIG. 2(F).
In the paper making process, the manufacture of a paper-type RFID tag is completed by disposing an RFID thread 37, formed by stacking the protective member 34, the antenna 32a and the polyester film 33 one on top of another, between first and second paper layers 38a and 38b, and finally heating and pressing the RFID thread 37 and the first and second paper layers 38a and 38b, as shown in FIG. 3.
In the above-described Korean Unexamined Patent No. 2005-79621, the process of manufacturing the RFID thread 37, formed by stacking the RFID chip 13, the protective member 34, the antenna 32a and the polyester film 33 one on top of another, is excessively complicated. Furthermore, adhering is performed through heating and pressing after the RFID thread 37 is disposed between the first and second paper layers 38a and 38b. However, since the first and second paper layers 38a and 38b have low strength and are vulnerable to humidity, they are easily deformed, so synthetic resin, such as the material of the polyester film (including the protective member), is used to increase the strength thereof, with the result that the problem of air contamination at the time of discarding through incineration still remains.
Furthermore, since the first and second paper layers 38a and 38b are vulnerable to humidity, they are easily peeled from the RFID thread 37 in the case where the paper RFID card falls into water or gets wet in the rain, so that it has many problems related to being put to practical use.